Heretofore, a radio relay device for relaying data transmitted and received by a first radio communication device such as a radio base station and a second radio communication device such as a radio terminal has been widely used (see Patent Document 1, for example). Such a radio relay device includes a first transceiver for performing first transmission and reception of transmitting and receiving data to and from the first radio communication device, and a second transceiver for performing second transmission and reception of transmitting and receiving data to and from the second radio communication device.
The time division duplex (TDD) scheme is known as a scheme for achieving bidirectional transmission in a radio communication system. In the TDD scheme, each of communication time frames (communication frames) segmented on a time axis is provided, by time sharing, with a first time period for transmitting data from the first radio communication device to the second radio communication device (a downstream frame, for example), and a second time period for transmitting data from the second radio communication device to the first radio communication device (an uplink frame, for example).
In a case of using the radio relay device in a radio communication system employing the TDD scheme, reception of data by the first transceiver from the first radio communication device and transmission of data by the second transceiver to the second radio communication device are performed simultaneously during the first time period. Similarly, reception of data by the second transceiver from the second radio communication device and transmission of data by the first transceiver to the first radio communication device are performed simultaneously during the second time period.
Accordingly, a radio wave emitted from an antenna of the second transceiver in the first time period propagates to an antenna of the first transceiver, and a radio wave emitted from the antenna of the first transceiver in the second time period propagates to the antenna of the second transceiver. Such propagation is problematic in that the first transceiver and the second transceiver affect each other by mutual interference.